Verify that the applet host entry in database (egpl_pref_globalsettings table of Active DB) has the correct server IP address, by running the following query: select * from egpl_pref_globalsettings where setting_name = ‘Common.messaging.applethost’

Verify java console output on client side for errors logged in a format similar to JAVA exceptions (see screenshot). Click View -> Java Console on IE.